/*
 * Copyright [2020-2030] [https://www.stylefeng.cn]
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Guns采用APACHE LICENSE 2.0开源协议，您在使用过程中，需要注意以下几点：
 *
 * 1.请不要删除和修改根目录下的LICENSE文件。
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 */
package cn.stylefeng.roses.kernel.rule.tree.factory;

import cn.stylefeng.roses.kernel.rule.tree.factory.base.AbstractSortedTreeNode;
import lombok.Data;
import lombok.EqualsAndHashCode;

import java.math.BigDecimal;
import java.util.*;
import java.util.stream.Collectors;

/**
 * 带排序功能的树构造器
 *
 * @author fengshuonan
 * @since 2024/9/7 20:53
 */
@EqualsAndHashCode(callSuper = true)
@Data
public class SortedTreeBuildFactory<T extends AbstractSortedTreeNode<T>> extends DefaultTreeBuildFactory<T> {

    public SortedTreeBuildFactory() {
        super();
    }

    public SortedTreeBuildFactory(String rootParentId) {
        super(rootParentId);
    }

    @Override
    public List<T> doTreeBuild(List<T> nodes) {
        if (nodes == null || nodes.isEmpty()) {
            return new ArrayList<>();
        }

        // 构建父节点到子节点的映射，键为父节点ID，值为子节点列表（已排序）
        Map<String, List<T>> parentIdToChildren = new HashMap<>();
        for (T node : nodes) {
            String parentId = Optional.ofNullable(node.getNodeParentId()).orElse(getRootParentId());
            parentIdToChildren.computeIfAbsent(parentId, k -> new ArrayList<>()).add(node);
        }

        // 对每个父节点下的子节点按排序值排序
        for (List<T> children : parentIdToChildren.values()) {
            children.sort(Comparator.comparing(
                    item -> Optional.ofNullable(item.getSort()).orElse(BigDecimal.valueOf(Integer.MAX_VALUE))
            ));
        }

        // 获取顶级节点：父ID为rootParentId的节点
        List<T> topLevelNodes = parentIdToChildren.getOrDefault(getRootParentId(), new ArrayList<>());

        // 递归构建子树
        topLevelNodes.forEach(topNode -> buildChildren(topNode, parentIdToChildren));

        return topLevelNodes;
    }

    /**
     * 递归构建子节点
     */
    private void buildChildren(T node, Map<String, List<T>> parentIdToChildren) {
        List<T> children = parentIdToChildren.get(node.getNodeId());
        if (children == null) {
            node.setChildrenNodes(Collections.emptyList());
            return;
        }
        node.setChildrenNodes(children);
        children.forEach(child -> buildChildren(child, parentIdToChildren));
    }

}
